Method of insulating a clip



14, 1956 c. E. FEIGHNER 2,758,947

METHOD OF INSULATING A CLIP Filed May 2, 1952 mm ."17 if a Mil M41 'I///////"////////// @3554 :1 Z 4- onrr va 6141/06 5. Ff/G/l/Vie United States Patent Ofice 2,758,947 Fatented Aug. 14, 1956 METHOD OF INSULATING A CLIP Claude E. Feighner, Torrance, Califi, assignor t o Northrop Aircraft, Inc., Hawthorne, Califi, a corporation of California Application May '2, 1952, Serial No. 285,701

4 Claims. (Cl. 117-212) My invention relates to insulated clips and more particularly to a means and method of insulating electrical connection clips known in the art as alligator jaw or alligator clips.

Alligator clips have widespread use in making temporary electrical connection to wires, terminals, or other electrical conductors. Often when two such clips are applied to closely spaced electrical conductors, shorting may occur, resulting in the burnout of a valuable meter or other expensive apparatus. The clip of the present invention is, for example, of great use in checking mathematical computing machines which use hundreds of closely spaced components such as germanium diodes.

Among the objects of the present invention are:

To provide a thin insulating coating on the jaws of alligator clips;

To provide a means insulating the jaws of alligator clips without substantially changing the dimensions thereof; and

To provide a method of coating the jaws of alligator clips with a thin coating of insulating material without coating the serrated edges or such portions of the jaws as are customarily used for electrical contact.

In brief, the present invention in one preferred form provides for the coating of the jaws of electrical connectors known in the art as alligator clips, by causing the uncoated jaws to clamp a small piece of elastic material, such as sponge rubber, between them. As such clips are designed to cause the jaws to close under spring action, merely placing the sponge rubber between the serrated edges of the jaws of an assembled clip will cause the opposing serrated edges of the jaws to be in contact with and slightly buried in the rubber. In most alligator clips these opposing surfaces are toothed, and by spring action, these teeth sink into and indent the rubber.

While the rubber is held between the serrated edges of the jaws, the entire nose of the clip is covered with insulating material in liquid form, this material then being dried or otherwise processed to form a thin adherent insulating coating on the jaws of the clip. The jaws are then opened and the rubber is removed. The teeth or other portions of the jaws protected by the rubber will not be coated, and will remain clean for electrical contact purposes. The amount of uncoated area on the jaws can be regulated to some extent by varying the softness of the gripped resilient material, thereby controlling the depth to which the serrated edges of the jaws can sink into the material.

My invention will be more fully understood by reference to the accompanying drawings in which:

Figure l is a side view of a standard alligator clip.

Figure 2 is a perspective view of a clip prepared for dipping.

Figure 3 is a view partly in section and partly in elevation showing the prepared clip being dipped in insulating material in liquid form.

Figure 4 is a side view of a dipped clip after drying of the insulation and removal of the serrated edge or tooth protecting material.

Figure 5 is a cross sectional view taken as indicated by the line 5-5 in Figure 4.

Figure 6 is a view partly in section and partly in elevation showing clips made in accordance with the present invention in use as electrical connectors.

Figure 7 is a perspective view of a tooth protector penetrated by the teeth of a clip prior to spray coating the jaws thereof.

Referring first to Figure 1, an alligator clip of conventional design is shown having a primary arm 1 provided with an electrical connection screw 2. Primary arm 1 is bent adjacent the screw 2 at a small angle, and then is bent again to pass through an aperture 3 in a secondary arm 4 similarly but oppositely bent, and arm 1 is then bent again to terminate in an underlapping jaw 5. The secondary arm 4 is attached to primary arm 1 adjacent screw 2 by tabs 6 passing through the primary arm 1 and loosely crimped to form a hinge. Secondary arm 4 is continued at the other end generally parallel with jaw 5 to form an overlapping jaw 7, opposed to underlapped jaw 5. Both jaws 5 and 7 are provided with serrations or teeth 10. The jaws are kept closed by arm spring 11 bearing internally on the arms 5 and 11 between the hinge and aperture 3. The edges of the arms are usually bent over into a U section for strength. Pressure with the fingers at points indicated by the arrows in Figure 1 will open the jaws of the clip against the pressure of spring 11.

In preparation for coating, the jaws 5 and 7 are opened and a small piece of material 12 such as sponge rubber for example, is placed between the jaws 5 and 7 and the spring 11 released. The pressure of the spring 11 causes the serrations or teeth 10 of the jaws to sink into the soft material 12, as best shown in Figures 2 and 3. In this case, the elastic material is deformed and temporarily indented, rather than cut.

As shown in Figure 3, the jaws 5 and 7 of the clip still clamping the elastic material, is dipped into insulating material 14 in liquid form, removed, and the coating dried. If desired, there can be several coats applied in the same manner. After the coating or coatings have dried, the jaws 5 and 7 are opened and the elastic material 12 removed.

As shown in Figure 4, the teeth 10 on the overlapping jaw 7 will not be coated, and as shown in Figure 5, the teeth 10 on the underlapping jaw 5 will likewise be uncoated, as they were embedded in the elastic material 12 when dipping and drying occurred. The remainder of the jaws 5 and 7 will be completely covered by a dense adherent film coat 15 of insulating material.

The coating material can be of many types. Liquid Bakelite for example when used as the dipping liquid can be used to provide a final hardened coating of from about .001 to .005 inch in thickness, and the latter thickness has been found to withstand potentials of over 1500 volts. Two such clips A and B, as shown in Figure 6, can be provided with connection wires 20 and rubber sleeves 21 when attached to electrical connect-ions 22 can safely touch even though the voltage between the clips is 1000 to 2000 volts, for example.

However, I do not wish to be limited to any particular type of insulating materials used to form the insulating coating, as many such materials are well known in the art for use as insulating varnishes and plastic coatings for wire and the like. For example, cellulose acetate dissolved in Plastacele type solvents provides, when dry, a tough adherent film of high insulating qualities.

Furthermore, while I have described the teeth of jaws 5 and 7 as being embedded by pressure in elastic material 12 so that the insulating compound can be removed therefrom and the pad reused, teeth 10 can equally well be protected during the coating process by being forced into a material that can be cut and penetrated by the teeth so that they will be buried in the material which will similarly protect the teeth 10 from the coating material. In this case, a small piece of soft card-board 25, for example, can be used between the jaws and whatever pressure is needed applied to the jaws *to force the teeth into the cardboard, as shown in Figure 7.

#In addition, while the dipping process ;is preferred, the

insulating material in liquid form can be applied to the jaws 5 and 7, after they have the serrations or teeth thereof protected, in other ways, as by spraying, painting, or flowing the liquid onto the jaws. A nozzle 8 is shown as coating jaws 5 and 7, in Figure 7.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise a-preferred -form ofputting the invention into effect, and the invention is therefore claimed in any of its iorms or modifications within the legitimate and valid scope of the appended claims.

What is claimed-is:

1. The method of insulating opposed elongatedserrated edges of the jaws of an electrical connection clip of the alligator jaw type; which comprises clamping the jaws of the clip on a material into which the teeth of the elongated serrated edges of the jaws will sink, whereby the teeth are embedded in the material applying a vthin liquid coating of insulating material to the exposed portions of the jaws, drying said coating, and unclamping the jaws of the clip and removing said clamped material to expose the uncoated teeth protected by said material.

2. Method in accordance with claim 1 wherein said material is a resilient material.

3. Method in accordance with claim :1 wherein said materia uis cardboar penet at d by d teeth.

4; M hod i acqrdan -c a 1 re saitla terial is a rubber-like material.

References Cited in the file of this patent STATES PATENTS Great Britain July '21, 

1. THE METHOD OF INSULATING OPPOSED ELONGATED SERRATED EDGES OF THE JAWS OF AN ELECTRICAL CONNECTION CLIP OF THE ALLIGATOR JAW TYPE; WHICH COMPRISES CLAMPING THE JAWS OF THE CLIP ON A MATERIAL INTO WHICH THE TEETH OF THE ELONGATED SERRATED EDGES OF THE JAWS WILL SINK, WHEREBY THE TEETH ARE EMBEDDED IN THE MATERIAL APPLYING A THIN LIQUID COATING OF INSULATING MATERIAL TO THE EXPOSED PORTIONS OF THE JAWS, DRYING SAID COATING, AND UNCLAMPING THE JAWS OF THE CLIP AND REMOVING SAID CLAMPING MATERIAL THE EXPOSE THE UNCOATED TEETH PROTECTED BY SAID MATERIAL. 